Glenoid and humeral bone loss is a crucial determinant of recurrent anterior shoulder instability. Bone defects (erosion-type or fragment-type bone loss on the glenoid, and Hill-Sachs lesion on the humerus) can be measured through different imaging modalities, but 3D CT is considered the gold standard. In the mid-range of motion, an important contributor to joint stability is the concavity of the glenoid bone. At the end-range of movement, a key role in producing instability events is played by the bipolar bone loss, the assessment of which is decisive for managing shoulder instability. Since it is a method to preoperatively analyze the entity of bipolar bone loss, we can use the glenoid track concept to better determine when to recommend surgical treatment and which surgical procedure is best for each patient suffering from anterior shoulder instability. With this concept, it is possible to distinguish on-track from off-track Hill-Sachs lesions, depending on whether or not they are entirely lateral to the medial margin of the glenoid track (the contact area created by the glenoid on the humeral head during the posterior end-range of motion), and predict the possibility of engagement of Hill-Sachs lesions with the anterior glenoid rim after a Bankart repair has been performed.